The target density is of a form inspired by the target densities in [1]}):
\(p(\theta _1,\theta _2) &= \frac{1}{3}\sum _{i=1}^3p_i(\theta _1, \theta _2)\\p_i(\theta _1,\theta _2)&\propto \exp {[\cos (\theta _1 - a^1_i)+\cos (\theta _2 - a^2_i)]}\) 
